. . . A 235 has max torque at 2000rpm so gear it to run a 2000 at the cruising speed you want. Anything above or under this engine speed will cost you at the gas pump. . . .
I know nothing about the optimum horsepower for balancing maximum torque and fuel efficiency.
However, if I am reading
this 1959 235 truck diagram correctly, maximum horsepower is achieved at about 3200 RPM on this diagram (max torque at about 1600 rom). And, the torque vs horsepower cross-over RPM is around 2600 RPM.
I can run all day at 60-65 mph in my 1954 Suburban (2500 RPM). I did it recently for an 8 hour drive to Macungie, PA. All "original equipment" front-end and brake equipment is in excellent condition; and, the truck has highway-speed radial truck tires on original wheels.
